One of our church members bent this rod on our John Deere mower. Try as I did I could not bend it back .... until applying heat from a propane torch.They took the impact just fine, it is the fire that took them down, I do not know about steel, 40 vs 60, but it would not matter either way, they both would soften the same from that temperature. the design flaw was that all stairways were in the core that got cut off, so people, could not leave upper floors. it they had emergency stairwells in corners , or close to them, on all 4 sides, people would escape, but corner space offers best bucks, corner offices are the what every cfo/ceo wants, multi million dollars apartments must have corner rooms for the view, so builders maximize value of rentable space, so safety comes after profits. not to mention such events are extremely rare, so no one, at least before 911 would put staircases where most desirable spaces are.
Ta Da! Back in service. Metal working 101.